1. Field of the Invention
This invention relates to a nut assembly having a nut element that is integrally connected to and movable rotationally and longitudinally relative to a washer so as to deform the washer and thereby mechanically lock the nut assembly to an associated bolt to prevent the inadvertent removal of the bolt from the nut assembly due to vibration and similar mechanical forces.
2. Background Art
The conventional two-piece fastener assembly 1 comprising a separate collar 2 and washer 4 is briefly described when referring to FIGS. 1 and 2 of the drawings. In the as-packaged configuration before installation, and is best shown in FIG. 1, the collar 2 includes a hollow body 6 having an internally threaded, hex-shaped head 8 at one end thereof and a relatively thin cylindrical shank 10 at the opposite end. The washer 4 also includes a hollow body 12 having a dish-shaped cavity 14 formed in one end thereof.
FIG. 2 shows the fastener assembly 1 of FIG. 1 after installation for securing a pair of sheet metal panels 60 and 70 together. More particularly, the collar 2 and washer 4 are first axially aligned with one another, and a commercially available (e.g. titanium) bolt or pin 16 is then inserted through holes in sheet metal panels 60 and 70 and into the hollow bodies 6 and 12 of collar 2 and washer 4 to connect said collar and washer together. The bolt 16 is of the type having a series of screw threads 18 at the forward end thereof, a flat head 20 at the opposite end, and a relatively narrow annular groove 22 located between the threaded end 18 and head 20. During tightening of the fastener assembly 1, the collar 2 is pulled towards washer 4 by bolt 16. Accordingly, the shank 10 of collar 2 is received within the cavity 14 of washer 4. A compressive force applied by washer 4 to shank 10 causes said shank to be bent or deflected inwardly towards the intermediate groove 22 of bolt 16. The position of the deflected shank 10 relative to the groove 22 forms a stop to prevent the bolt from withdrawing past shank 10 and inadvertently rotating out of engagement with threaded collar 2 as a consequence of vibration and similar mechanical forces to which the fastener assembly 1 is subjected.
The conventional two-piece fastener assembly 1 illustrated in FIGS. 1 and 2 is characterized by several shortcomings. First, there are a plurality of separate members (i.e. a collar 2 and a washer 4) to be handled which increases the assembly time and the possibility that fastener members may be lost or misplaced. Moreover, the washer 4 must first be oriented relative to collar 2 such that the shank 10 of collar 2 and the dish-shaped cavity 14 of washer 4 are aligned end-to-end one another during installation. Sometimes, the washer 4 is incorrectly installed with the cavity 14 facing away from shank 10, whereby to reduce the locking ability of the fastener assembly and the reliability for preventing removal of the bolt 16. What is more, it is relatively difficult to remove the bolt 16 and separate the washer 4 from the collar 2 when it is necessary to disconnect fastener assembly 1 from the panels 60 and 70 after installation.